April 25, 2008

Following up on my previous post, I thought it might be interesting to look at the strength of the opposing lineups that individual players faced, rather than looking at five-man units as a whole. The basic idea is the same. I used lineup data from BasketballValue, and for each player I calculated a weighted average of the season defensive ratings of the opposing lineups that they faced, weighted by the number of possessions they played against each opposing lineup. In the tables below I excluded players who were on the court for less than 1000 offensive possessions.

That’s a pretty interesting list. There are a lot of players from great offensive teams. Maybe this is saying that those offenses weren’t so much great as they were lucky - they had the good fortune of facing weaker defensive lineups than other teams faced. But I don’t think this conclusion is warranted. I can think of a few other theories to explain some of the entries on this list.

First, an obvious place to look for players who faced weak defenses would be backups to offensive stars. If a team is facing the Lakers, they will probably try to have their top perimeter defenders in whenever Kobe is in the game. When he goes to the bench, their best defenders will rest too. So Kobe’s backups often have the advantage of facing lesser defenders. This theory could help explain the presence of a number of players in the table above.

Second, there are a number of players on the list from undersized or small-ball teams like Golden State, Orlando and Phoenix. One explanation for this could be that to match up with such teams, opponents often go small as well. For the purposes of that particular game, this could be the best defensive strategy. But on the season as a whole, these makeshift undersized lineups won’t fare very well defensively. So it could just be the case that teams like Golden State typically face lineups that are poor defensively in normal circumstances (i.e. when facing regular-sized teams).

I find this list harder to interpret. It seems to be made up of worse players from worse teams compared to the first list. Probably a lot of it is just randomness - no matter what, some players have to face better defensive lineups. Beyond that, I’d be interested to hear any theories people might have.

In theory, one could use these kinds of adjustments to identify players whose offensive stats may have been inflated (or deflated) based on the level of defenses that they went up against. Of course, one would have to take into account alternative explanations like the small-ball theory, and consider the fact that when a player faces a lineup that’s poor overall defensively that doesn’t mean that the individual player guarding them was a poor defender.

Here is a Google Spreadsheet containing the data for all players from this past season.

One of the obvious affects on the second table is the higher than average numbers of stars and good offensive lineups. If, as you posit, the strongest defenders are paired with the strongest offensive players, then the numbers for the defenses will suffer. When Battier shadowed Kobe, everyone praised his fantastic defense, but Kobe went for 45,30, & 24 this season against Houston. If, as one would suspect, this happens to Battier not just on Kobe, but all season long against all SG & SF opponents, then his defensive stats will suffer at some point, and therefore the stats for the lineups that he is a part of.

Intuitively, or from actually watching the games, we know that must be somewhat the case. Kobe always sees the best perimeter defender from opponents, and Duncan always sees the best post defenders, which would suggest that they must be seeing better overall defensive lineups, yet they don’t show up in the list.

I guess this is a convoluted way of saying that maybe the offensive ineptitude of those on the list helps the defenses look good statistically.